1. Field of the Invention
The present invention relates to a compact wrench. In particular, the present invention relates to a compact wrench with three-stage control, allowing the wrench to be in one of three operating states.
2. Description of the Related Art
FIG. 11 of the drawings illustrates a conventional wrench comprising a handle 10′ and a head 11′ formed on an end of the handle 10′. The head 11′ includes a compartment 12′ in which a wheel 20′ is rotatably mounted. Two pawls 30′ are mounted in cavity 14′ defined in the head 11′ and communicated with the compartment 12′. Each pawl 30′ includes a plurality of teeth 301′ on a side thereof for releasably engaging with teeth 21′ in an outer periphery of the wheel 20′. Each pawl 30′ further includes a peg 302′ on a lateral face thereof that faces the other pawl 30′, with a spring 31′ attached between the pegs 302′ on the pawls 30′. Further, each pawl 30′ includes a protrusion 303′ formed on an upper side thereof and extending through a slot 15′ into a control groove 13′ in a side of the head 11′.
A switching disc 41′ is pivotally mounted in the control groove 13′ by a pin 43′. The protrusion 303′ of each pawl 30′ extends into a groove 412′ in the switching disc 41′, allowing the protrusion 303′ of the pawl 30′ to slide along the slot 15′ when the switching disc 41′ is turned. The switching disc 41′ further includes two tubular members 411′ each having a downward opening. A spring 44′ is mounted in a hole 131′ in a bottom wall delimiting the control groove 13′for biasing a ball 45′ into one of the tubular members 411′. A thumb turn 42′ is formed on top of the switching disc 41′ to allow manual switching of the switching disc 41′, allowing the ball 45′ to selectively engage with one of the tubular members 411′. When the ball 45′ is engaged one of the tubular member 411′, one of the pawls 30′ is engaged with the wheel 20′ whereas the other pawl 30′ is disengaged from the wheel 20′, allowing driving rotation in a first direction and free rotation in a second direction reverse to the first direction. When the ball 45′ is engaged with the other tubular member 411′, the originally engaged pawl 30′ is disengaged from the wheel 20′ whereas the other pawl 30′ is engaged with the wheel 20′, allowing driving rotation in the second direction and free rotation in the first direction.
The head of the wrench has a relatively large size, as a large compartment 14′ for receiving the pawls 30′ is required. Further, the arrangement for switching the driving direction is complicated and thus takes a long time to manufacture and assemble. The cost of the wrench is thus high.